How much does the average American Express cardholder spend in the iTunes store each month? A lot. And how often do you go to iTunes and change your default card? Never. Is it worth $5 to have your card powering an iTunes account? To American Express it is.

I'm sure the card company's spreadsheet shows a payback within a year or two on incremental interchange alone. But more important is the added stickiness these frequent Apple purchases give to the card. Plus, it can't hurt to associate your brand with the most valuable tech company on the planet.  

The fine print
To earn the five-song credit, cardholders must make a purchase with their Amex card between Feb. 10 and March 15. That earns a statement credit equal to five song downloads. It doesn't say which song price-point is used in the calculation, but I'm guessing the standard $0.99.

Relevance to Netbankers
It's always good business to get your card installed as an automatic payment source. Interchange goes up, credit card receivables improve, and you've added one more electronic hook to the account. So consider taking a similar approach and offering a small bounty after your card is used with a new biller.

iTunes promo on main Amex account page (Business Gold, 11 Feb. 2011)

Enrollment screen (link)